| Summary: | Topological materials and more so insulators have become ideal candidates for spintronics and other novel applications. These materials portray band inversion that is considered to be a key signature of topology. It is not yet clear what drives band inversion in these materials and the basic inferences when band inversion is observed. We employed a state-of-the-art ab initio method to demonstrate band inversion in topological bulk Bi2Se3 and subsequently provided a reason explaining why the inversion occurred. From our work, a topological surface state for Bi2Se3 was described by a single gap-less Dirac cone at k→ = 0, which was essentially at the Γ point in the surface Brilloiun zone. We realized that band inversion in Bi2Se3 was not entirely dependent on spin–orbit coupling as proposed in many studies but also occurred as a result of both scalar relativistic effects and lattice distortions. Spin–orbit coupling was seen to drive gap opening, but it was not important in obtaining a band inversion. Our calculations reveal that Bi2Se3 has an energy gap of about 0.28 eV, which, in principle, agrees well with the experimental gap of ≈0.20 eV–0.30 eV. This work contributes to the understanding of the not so common field of spintronics, eventually aiding in the engineering of materials in different phases in a non-volatile manner.
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